Spatial resolution is an important indicator for measuring image quality in Tomography (CT) imaging technology. The spatial resolution may reflect the minimum limit of geometric dimensions of objects that can be recognized in an image. Therefore, theoretically speaking, the higher the spatial resolution is, the better the image quality will be. However, in the actual CT imaging system, the spatial resolution is affected by multiple factors such as focal spot size, reconstruction kernel, detector size and the like.
To enhance the spatial resolution, the traditional method is adjusting the convolution kernel in the reconstruction. A high-pass convolution kernel better preserves the high resolution of an image, but brings greater noise. A low-pass convolution kernel better suppresses the noise, but the resolution is limited. The convolution kernel plays a role of balancing the noise and the resolution. However, the high-pass of a convolution kernel has frequency limitation. When it is higher than a certain frequency, a further resolution increase will instead induce greater noise, and more artifacts, while the limit frequency of a system is limited by the detector size and the way of sampling.
Another method for enhancing the spatial resolution is filtering in a direction of a detector channel, which is mainly used to solve a boundary blur caused by the secondary scattering of the tube in the system.
However, none of the above methods can solve an image blur caused by the coupling of the adjacent sampling views for the same detector channel.
Thus, the present invention is intended to explore the coupling relationship between data views: that is, for a certain detector, there is a repeated area across which the ray beams scan, between the adjacent views. The enhanced filtering in the view direction of the present invention is just to remove the coupling relationship of this part, and thereby solve the blurring problem caused in the view direction.